What is the industry standard for determining the grade of mains and circuits in heating systems?

The industry standard for determining the grade of mains and circuits in heating systems is based on the practical requirements for proper drainage and the flow of condensate. A slope of 1 inch per 20 feet is commonly accepted because it provides sufficient pitch to facilitate drainage. This enables condensate to flow effectively back towards the return system, preventing the buildup of water within the pipes, which could lead to inefficiencies or damage.

Using a slope that is too steep may disrupt the flow of steam or create issues with backpressure, while a slope that is too shallow might not allow condensate to escape properly, leading to possible water hammer or erosion within the system. This standard ensures an effective balance between proper condensate drainage and maintaining an efficient steam flow throughout the heating system.